From the Windows Phone Marketplace team…Top seven items to check in order to pass certification.
1. Technical Support Information. Include technical support contact information, such as an email address or URL, within the application along with the application version number.
2. Content Validation. Be sure that application visual elements are visible and legible in both Windows Phone 7 light and dark themes. The application description, the UI text, and media within the application must be in the corresponding target language the XAP supports.
3. Application Termination. Applications must provide a user-friendly error message when an application terminates unexpectedly.
4. Application Screenshot. Screenshots must not include any emulator chrome, be graphically enhanced, or use transparent PNG image files.
5. Windows Phone Marketplace Iconography. Icons must closely match the icon provided in the XAP package.
6. Declaring Application Capabilities. Use the method documented on MSDN regarding How to: Use the Windows Phone Capability Detection Tool. Pay close attention when referencing the WebBrowser control and be sure to access it from code-behind.
7. Application Localization. Follow globalization and localization best practices on MSDN and test applications using multiple regional and language settings